Pre-Processing Filter Calibration in Time-Interleaved DACs
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Time interleaved digital-to-analog converter (TIDAC) systems experience frequency-dependent magnitude and phase mismatches between channels, leading to inaccuracies in the analog output signal.
Innovation Solution
A calibration operation is implemented to calibrate pre-processing filters associated with each TIDAC channel, using a desired frequency response and actual frequency response to correct for mismatches, involving the use of a combiner to combine analog signals and a correction filter processor to determine pre-processing filter coefficients that minimize approximation errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple time interleaved DAC channels are used to achieve higher effective sampling rate, then productivity is improved, but manufacturing precision deteriorates due to frequency-dependent magnitude and phase mismatches between channels
Solution Approach 1:
The patent applies preliminary action by implementing calibration procedures that measure and characterize the magnitude and phase mismatches between DAC channels before actual operation. Correction filters are designed and applied in advance to compensate for these mismatches, ensuring accurate output signals while maintaining the high effective sampling rate achieved through time interleaving
Solution Approach 2:
The patent applies parameter changes by adjusting the frequency response characteristics of correction filters to compensate for mismatches. The calibration process determines specific magnitude and phase correction parameters for each channel, and these parameters are applied to equalize the overall system response across all time interleaved channels
2Manufacturing precision
If calibration procedures are implemented to correct channel mismatches, then manufacturing precision is improved, but device complexity increases due to additional correction filters and calibration operations
Solution Approach 1:
The patent introduces correction filters as intermediary components between the time interleaved DAC channels and the output combiner. These filters act as mediators that compensate for channel mismatches without requiring fundamental changes to the DAC architecture, thereby improving accuracy while adding only moderate complexity through filter implementation
Solution Approach 2:
The calibration system applies self-service by automatically measuring the frequency responses of individual DAC channels and generating appropriate correction filter parameters without requiring manual adjustment. The system performs self-characterization and self-correction, reducing the need for external calibration equipment and simplifying the overall calibration process
Data Source
AI summary
A time interleaved digital to analog converters (TIDACs) system having a pre-processing filter to filter a digital signal prior to being converted by a respective digital-to-analog converter (DAC) of the TIDACs system to correct for mismatches between the DACs of the TIDACs system. Calibrating the pre-processing includes converting a discrete waveform at a first DAC to a first analog signals and at a second DAC to a second analog signal and combining the first and second analog signals into a combined signal. An analog-to-digital converter (ADC) converts the combined signal to a digital signal to determine an actual frequency response of the TIDACs system. A desired frequency response of the TIDACs system is received and a pre-processing filter is generated for the first DAC and the second DAC based on the actual frequency response of the TIDACs system and the desired frequency response of the TIDACs system.